According to the data, more than 80% of the affected children occur under the age of 5, with a median age of 1.5 years. Because the immune system of children under 5 years of age is not yet mature, it is more likely to develop after the child is 6 years old. There are also some patients who are older than 6 months of age, because children younger than 6 months of age are less susceptible to the disease because they still have antibodies brought from their mother’s body. Kawasaki disease can cause heart damage, such as coronary artery dilation and coronary artery aneurysm.